.main {
    border: solid 10px blue;
}

.one {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: bisque;
    width: 100%;
    height: 100px;
}

button {
    margin: 10px;
}

.two {
    background-color: green;
    width: 100%;
    height: 600px;
}

.two>div {
    width: 50px;
    height: 50px;
    background-color: aqua;
    margin: 10px;
    float: left;
    line-height: 50px;
    text-align: center;
    border: solid 5px rgb(8, 163, 235);
}

.two>div:nth-child(odd) {
    background-color: brown;
}

.two>div:hover {
    background-color: black;
    cursor: pointer;
    border-color: black;
}